title: Solvation studies of a zinc finger protein in hydrated ionic liquids.
abstract: The solvation of the zinc finger protein with the PDB-ID “5ZNF” in hydrated ionic liquids was studied at varying water content. 1-Ethyl-3-methylimidazolium and trifluoromethanesulfonate were the cation and anion, respectively. The protein stability as well as the solvation structure, the shell dynamics and the shell resolved dielectric properties were investigated by means of molecular dynamics simulations. The lengths of the respective trajectories extended up to 200 nanoseconds in order to cover the complete solvent dynamics. Considering the above mentioned properties as a function of the water content they all exhibit a maximum or minimum at the very same mole fraction. While the exact value x(H(2)O) = 0.927 depends on the underlying force field, its origin may be traced back to the competition between the van der Waals and the electrostatic energy of the protein as well as to the transition from aqueous dielectric screening to ionic charge screening with decreasing water content. The parameter-free Voronoi decomposition of space served as a basis for the analysis of most results. In particular, solvation shells were naturally inferred from this concept. In addition to the molecular analysis a mesoscopic view is given in terms of dielectric properties. Thereby, the net dielectric constant is decomposed into contributions from the protein, the first and second solvation shells as well as the bulk. Cross-terms between these components are given, too.
authors.affiliation: University of Vienna, Department of Computational Biological Chemistry, Währingerstr. 17, 1090 Vienna, Austria.
authors.forename: Michael
authors.initials: M
authors.lastname: Haberler
authors.forename: Christian
authors.initials: C
authors.lastname: Schröder
authors.forename: Othmar
authors.initials: O
authors.lastname: Steinhauser
mesh_terms: D052578:Ionic Liquids / Q000737:chemistry*; D008958:Models, Molecular; D055550:Protein Stability; D011506:Proteins / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry*; D013816:Thermodynamics; D016335:Zinc Fingers
chemical_list: D052578:Ionic Liquids; D011506:Proteins; D012997:Solvents